Bug #16305: GDM's GNOME Shell floods the Journal with XFIXES/cursor issues on Buster

Bug #16305

GDM's GNOME Shell floods the Journal with XFIXES/cursor issues on Buster

Added by CyrilBrulebois 2019-01-06 02:36:26 . Updated 2020-04-15 06:02:19 .

Status:

Resolved

Priority:

Elevated

Assignee:

Category:

Hardware support

Target version:

Tails_4.0

Start date:

2019-01-06

Due date:

% Done:

100%

Feature Branch:

Type of work:

Code

Blueprint:

Starter:

Affected tool:

Welcome Screen

Deliverable for:

Description

On feature/buster, a few seconds after logging in:

amnesia@amnesia:~$ sudo journalctl | grep -c 'gnome-shell.*: Failed to create XFIXES cursor: Failed to get cursor image'
[sudo] password for amnesia: 
9398

I think we might have a cursor issue.

In case that matters, this is through virt-manager/libvirt.

Subtasks

Related issues

Related to Tails - Feature #12213: Wayland in Tails 5.0 (Bullseye)	In Progress	2017-09-02
Related to Tails - ~~Bug #12092~~: The Greeter keeps eating lots of memory after logging in	Resolved	2016-12-27

History

#1 Updated by intrigeri 2019-01-06 07:03:49

Status changed from New to Confirmed

Would be interesting to try & reproduce this on pristine Debian testing/sid (explicitly opting in for a GNOME X.Org session).

#2 Updated by CyrilBrulebois 2019-01-06 11:34:05

Here are the options I’m getting after a default (French) installation of the GNOME desktop with D-I Buster Alpha 4:

System X11 Default
GNOME
GNOME Classique

and none of them exhibits the XFIXES issue seen in Tails.

#3 Updated by intrigeri 2019-01-06 11:48:51

Type of work changed from Code to Research

FWIW I can’t reproduce the bug with a feature/buster build at commit:b8a9438cbb55ba053f4b6a701f8995e5edfa2d0d (libvirt, Spice, virtio-gpu). I only see Initializing extension XFIXES twice (once for the GDM X session, once for the amnesia session).

Wrt. reproducing on testing/sid: to tell whether a GNOME session is using X.Org, check $XDG_SESSION_DESKTOP; if using Wayland, the value will be gnome; if using X.Org, it’ll be gnome-xorg. “GNOME on Xorg”. I’m pretty sure the 2 GNOME sessions you see are using Wayland; no idea about the X11 thing. I think you want /usr/share/xsessions/gnome-xorg.desktop (“GNOME on Xorg”). I see it on a Debian sid installation (it might be that GDM only displays it under some conditions); there I don’t see XFIXES issues in the Journal.

So I’m curious what exactly triggers this problem in your setup and not on mine. I’ll test this on bare metal.

#4 Updated by CyrilBrulebois 2019-01-06 11:59:06

Right, those names didn’t seem to match what you were suggesting.

FWIW I’m seeing this with my local branch (with only commits in features/) which is on top of current feature/buster, that is commit:7b5447201a5798abc6ba58facd581f2fa051fa7 (a few commits later than you). I’m not setting anything specific on the libvirt/virt-manager side, so I’m on llvmpipe on the rendering side. Maybe that’s why I’m not offered the same options as you are? I do see the said gnome-xorg.desktop file in the installed system.

Regarding the XDG_SESSION_DESKTOP, I’m seeing respectively:

default
gnome
gnome

so no gnome-xorg indeed.

#5 Updated by intrigeri 2019-01-06 12:24:54

Can’t reproduce with a feature/buster build at commit:b8a9438cbb55ba053f4b6a701f8995e5edfa2d0d on bare metal (ThinkPad X200).

Reproduced with the same ISO on a VM created with virt-manager on sid, with the default settings (QXL graphics, Spice display, generic PS2 mouse). Note that the issue is only about GDM’s session (/usr/bin/gnome-shell --mode=gdm-tails), not about the “amnesia” one.

Hint: git grep set-cursor.py in greeter.git. I suspect that’s the culprit. No idea if we still need this, iirc it’s meant to display a “waiting” cursor while the Greeter is running or while logging in, or similar.

#6 Updated by intrigeri 2019-01-07 14:28:25

The code that logs this error seems to be https://sources.debian.org/src/mutter/3.30.2-4/src/backends/meta-cursor-tracker.c/?hl=229#L229

#7 Updated by intrigeri 2019-01-07 14:49:26

So, https://sources.debian.org/src/mutter/3.30.2-4/src/backends/x11/cm/meta-cursor-sprite-xfixes.c/?hl=105#L133 calls XFixesGetCursorImage which fails in this context (QXL, GNOME on X.Org). Same problem with Cirrus graphics but works fine with virtio-gpu. My understanding is that this code is not called under Wayland.

Next steps:

Reproduce on pristine Debian with GNOME on X.Org so we can report the problem upstream.
Most likely our test suite is affected and flooding the Journal can cause all kinds of trouble => switch the test suite to virtio GPU (assuming the virt host supports it).
To be ready in case that’s not fixed in Buster, update our end-user doc about libvirt virtualization to recommend a GPU that works well and is not affected by this bug (most likely virtio, which works as well as QXL in my experience, is the current dev focus, and has host-accelerated 3d support on Buster — for which I need to fix some AppArmor things by the way).

#8 Updated by intrigeri 2019-01-07 14:49:54

related to Feature #12213: Wayland in Tails 5.0 (Bullseye) added

#9 Updated by intrigeri 2019-01-07 14:54:11

Assignee set to intrigeri
Priority changed from Normal to Elevated

(Should be reported upstream ASAP, winter is coming.)

#10 Updated by intrigeri 2019-01-07 14:55:20

Category set to Hardware support

(Not sure at this point if bare metal is affected but let’s play it safe and not assume only QEMU virtual GPUs are.)

#11 Updated by intrigeri 2019-01-07 16:28:14

related to ~~Bug #12092~~: The Greeter keeps eating lots of memory after logging in added

#12 Updated by intrigeri 2019-01-07 16:34:55

Affected tool set to Greeter

FTR our automated test suite is affected:

Jan 07 07:35:04 amnesia gdm-session-worker[5508]: Entering PostLogin
Jan 07 07:35:04 amnesia gdm-session-worker[5508]: Running /usr/local/lib/tails-unblock-network...
Jan 07 07:35:04 amnesia /usr/lib/gdm3/gdm-x-session[4408]: (II) config/udev: removing device spice vdagent tablet
Jan 07 07:35:04 amnesia /usr/lib/gdm3/gdm-x-session[4408]: (II) UnloadModule: "libinput"
Jan 07 07:35:04 amnesia /usr/lib/gdm3/gdm-x-session[4408]: (II) systemd-logind: releasing fd for 13:69
Jan 07 07:35:04 amnesia dbus-daemon[5543]: [session uid=1000 pid=5543] Activating via systemd: service name='org.gtk.vfs.Daemon' unit='gvfs-daemon.service' requested by ':1.1' (uid=1000 pid=5541 comm="gio set /home/amnesia/Desktop/Report_an_error.desk")
Jan 07 07:35:04 amnesia gdm-session-worker[5508]: + systemctl start tails-unblock-network.service
Jan 07 07:35:04 amnesia systemd[5512]: Starting Virtual filesystem service...
Jan 07 07:35:04 amnesia spice-vdagentd[4992]: closed vdagent virtio channel
Jan 07 07:35:04 amnesia systemd[1]: Starting Unblock network device drivers...
Jan 07 07:35:04 amnesia gnome-shell[4635]: Failed to create XFIXES cursor: Failed to get cursor image
Jan 07 07:35:04 amnesia gnome-shell[4635]: Failed to create XFIXES cursor: Failed to get cursor image

As the log shows, this happens as soon as logind removes the input device from GDM’s GNOME Shell. Initially I thought “oh, that’s because we keep GDM’s GNOME Shell instance running while Debian does not”, but that’s incorrect:

I can’t reproduce in a Debian sid VM with QXL graphics on a sid host. ~~Bug #12092~~ suggests that X.Org vs. Wayland matters so I’ve tried with a GDM and user session that use both X.Org, and there I can’t reproduce this problem there either and I see that GDM’s GNOME Shell instance is still running after login there, just like in Tails (3.x and feature/buster both).

So there’s nothing to report upstream and this seems to be a Tails Greeter specific problem => adding Alan to Cc. I’ll look into our cursor hacks and if they’re not at fault, I’ll try the hack proposed on ~~Bug #12999~~ and see if we can integrate it properly.

#13 Updated by intrigeri 2019-01-07 20:02:59

This works around this problem:

+--- a/usr/lib/python3/dist-packages/tailsgreeter/gui.py
++++ b/usr/lib/python3/dist-packages/tailsgreeter/gui.py
+@@ -883,9 +883,6 @@ class GreeterMainWindow(Gtk.Window, TranslatableWindow):
+ 
+     def finish_login(self):
+         logging.info("Starting the session")
+-        # /usr/lib/systemd/user/tails-greeter-session-helper.service will
+-        # restore the cursor to the left pointer state.
+-        self.get_root_window().set_cursor(Gdk.Cursor.new(Gdk.CursorType.WATCH))
+         self.greeter.login()
+         return False

Unfortunately, it removes a nice UX improvement brought by ~~Feature #5945~~. Other options that don’t have this drawback:

Keep this code but terminate the GDM session ASAP during the amnesia session setup (~~Bug #12092~~).
- Pros: we save memory.
- Cons: there will still be lots of error messages in the Journal until the GDM session is terminated.
Drop this code but add a user service that runs ASAP during the amnesia session setup and switches the cursor to hourglass (and then tails-greeter-session-helper.service resets the cursor back to its idle state).
- Pros: no errors in the Journal and we stop fiddling in GDM with the state of a cursor we don’t control anymore, which feels less risky.
- Cons: the cursor may be switched to hourglass too late, and not remain this way for long, so perhaps it’s more hassle than it’s worth.

#14 Updated by intrigeri 2019-01-07 22:12:56

Subject changed from gnome-shell flooding the journal with XFIXES/cursor issues to GDM's GNOME Shell floods the Journal with XFIXES/cursor issues on Buster
Status changed from Confirmed to In Progress
Type of work changed from Research to Code

intrigeri wrote:
> This works around this problem:
>
> […]
>
> Unfortunately, it removes a nice UX improvement brought by ~~Feature #5945~~.

I’ve tested feature/buster without this workaround on a ThinkPad X200 and that UX improvement is actually almost a no-op (at least on Buster; did not check on Stretch): the cursor turns to hourglass only for ~1 second; during most of the login process, either the cursor is entirely hidden or it’s back to the usual arrow. So it seems that dropping this “switch to hourglass after one clicks Start” does not impact UX much. Also, now that the login process does not block on installation of additional software anymore, one reason that made this UX improvement important is gone. So I’ll apply this workaround and will drop the code that deals with the cursor post-login.

#15 Updated by intrigeri 2019-01-07 22:26:45

Status changed from In Progress to Resolved
% Done changed from 0 to 100

Applied in changeset commit:tails|350f76ddab7a38cff00234e6388dd453fb816798.

#16 Updated by intrigeri 2019-01-07 22:27:07

Assignee deleted (~~intrigeri~~)

#17 Updated by intrigeri 2020-04-15 06:02:19

Affected tool changed from Greeter to Welcome Screen